Design/Build (Archived)

RT-133 Topic Summary
RT 133

Overview

RT-133’s charter was to evaluate the Design-Build (D-B) project delivery system, comparing its attributes and success measures to those of two other delivery systems commonly used in building construction: Design-Bid-Build (D-B-B) and Construction Management (CM) At Risk. The team studied the methods used considering project attributes, owner in-house needs and desires, and critical project success factors.

Through surveys and statistical analysis of over 350 projects, the research shows that projects using D-B methods experience significantly less cost growth than those employing D-B-B, and less than those employing CM at risk. Projects using D-B-B experienced the highest schedule growth, with D-B and CM at risk performing similarly on schedule performance. Lastly, quality measures associated with D-B projects were better than those with D-B-B projects.

Using the information collected, RT-133 developed:

  • “Project Data Sheets” characterizing the key attributes, owner responsibilities, and comparative strengths/weaknesses of each delivery method.  
  • The Project Delivery System Selection Workbook – a tool for use by owners to select the most appropriate project delivery system (D-B, D-B-B, or CM at risk) for their specific projects.                           

Key Findings and Implementation Tools

1 : Cost Growth

Design and construction cost growth was least (best) for the D-B method, approximately 2.4% (median), less than half that for the D-B-B method and approximately 35% lower than experienced by CM at risk projects. The frequency of D-B method projects experiencing >5% cost growth was also much lower than projects using other methods saw. (RS133-1, p. 6)
Reference: (RS133-1)

2 : Schedule Growth

Design and construction schedule growth was highest (worst) for D-B-B projects, at about 4.4% (median). Median schedule growth for D-B and CM at risk projects was right at 0%. The frequency of CM at risk method projects experiencing >5% schedule growth was lowest, followed by D-B projects; schedule growth was highest for D-B-B projects. (RS133-1, p. 8)
Reference: (RS133-1)

3 : Construction Speed

Median design and construction speed, measured as square feet completed per month, was highest for D-B projects and was over 2x that achieved by D-B-B projects and more than 50% higher than that achieved by CM at risk projects. (RS133-1, p. 9)
Reference: (RS133-1)

4 : Quality

Based on seven different measures of “quality,” all three delivery methods on average met or exceeded customer expectations. Within the subtle differences that existed, D-B scored overall higher than the other methods, with D-B-B trailing slightly. (RS133-1, p. 11)
Reference: (RS133-1)

5 : Public – Private Performance

The performance advantages for the D-B method were greater on private sector projects than for public sector projects. The greater flexibility in private sector bidding and contractor selection processes was the most common reasons cited for the greater effectiveness of D-B methods in the private sector. (RS133-1, p. 21)
Reference: (RS133-1)

6 : Implementation Tool #1

IR133-2, Project Delivery System Selection Workbook

This workbook will guide an owner or stakeholder of a facility through a project delivery selection process. Provides a flowchart and supporting templates for use by owners to:

  • Better understand each project delivery system and how each can impact their business
  • Identify the project delivery system for their particular project goals
  • Recognize key characteristics of highly successful projects and to create them on their own projects irrespective of which project delivery system is used 

Project Data Sheets. These data sheets reflect lessons-learned by survey respondents and contain team, owner and procurement attributes that need to be considered. (RS133-1, p. 24)

  • Construction Management at Risk Project Data Sheet 
  • Design-Build Project Data Sheet 
  • Design-Bid-Build Project Data Sheet 
Reference: (IR133-2)
rt-133

Key Performance Indicators

Improved cost, Improved schedule, Improved quality (reduced errors & omissions)

Research Publications

Project Delivery System Selection Workbook - IR133-2

Publication Date: 12/1999 Type: Implementation Resource Pages: 40 Status: Archived Tool

Project Delivery Systems: CM at Risk, Design-Build, Design-Bid-Build - RR133-11

Publication Date: 04/1998 Type: Research Report Pages: 185 Status: Archived Reference

Project Delivery Systems: CM at Risk, Design-Build, Design-Bid-Build - RS133-1

Publication Date: 12/1997 Type: Research Summary Pages: 34 Status: Archived Supporting Product


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